To stopping the flow in the protected area near Earth space man-made long space debris, in this case an upper stages of SLV with liquid propulsion engines (LPE) once they complete their mission, and to reduce the impact of lower stages in the impact footprints considered the development of an autonomous onboard deorbiting system (AODS), which provides deorbiting maneuver. As an example, SLV type "Souz-2.1.B" on propellants "oxygen- kerosene". To implement the deorbiting maneuver suggests the use of the energy resources contained in unused remains of liquid propellant in the tanks of stages SLV after main LPE off. Proposed AODS close to its basic purpose to the systems to used the second stage LPE: RL-10B-2 (SLV «Delta-4»), LE-5B-2 (SLV «H-IIB»), HM7-B (SLV «Ariane 5») for propellants "oxygen - hydrogen" are also implemented deorbit stages from orbit. Differences between the proposed schemes from the russian scheme are as follows: - instead of using a cryogenic hydrogen fuel high-boiling kerosene (russian SLV type "Souz", advanced "Angara"), which leads to the need for a multiple increase of heat input to the tank with fuel for the gasification of kerosene; - to implement the pulse in the AODS developed special gas propulsion engine (GPE), which has small dimensions and mass; - having regard to the russian specifics stages to bring in impact areas with dramatically reduced size, suggests the use of AODS both the first and the second stages of SLV; - additional placement of propellant on board to get the heat-carrier levels can guarantee to provide testing of the specified impulse. The main critical technology to create AODS is gasification of residues of liquid kerosene as they are in an uncertain boundary condition after the sustainer LPE off. The proposed gasification system is based on the feeding of the hot gas (heat-carrier) in the propellant tanks. It is made preliminary cost-effectiveness analysis of the use AODS, which has shown quick recoupment of this development.
Source

The complexity of the implementation of human spaceflight to the related art is so great, that of all the tasks carried out by the astronauts, only expensive repair satellites and space stations results in direct (justified, payback) results. Since manned stations themselves are the means for the existence of man in space, their repair can be treated bankable only conditionally-ie with respect to the funds spent on the creation of a space station. The amount of expensive satellites available to service manned spacecraft, is relatively small (in the range of 10-20 objects). A wider range of commercial services (such as space tourism, the media business, unique technologies testing, etc.) cannot yet justify the cost of the creation of manned space stations, ships. The level of financial expenses for the creation of a manned ship today more than 100 times biggest than a possibility of commercial investment in these services.
Source